| 摘要 |
<p>A piston (20) having a groove (22b, 22c) that is formed on a surface of a piston workpiece (20W) and a method for forming the groove (22b, 22c) on the piston (20). A head (22) of the piston (20) is accommodated in a corresponding cylinder bore. A first groove (22b, 22c) and a second groove (22b, 22c) are formed on the peripheral surface (22a) of the piston (20). The first groove (22b, 22c) scrapes lubricant oil from the inner surface of the cylinder bore and the second groove (22b, 22c) conveys the oil to the crank chamber. A coating layer (C) is formed on the peripheral surface (22a)of the head (22). The coating layer (C) is not formed on the areas that are designated for the first and second grooves (22b, 22c) on the peripheral surface (22a) of the head (22) of the piston workpiece (20W). Accordingly, the first and second grooves (22b, 22c) have a depth equal to the thickness of the coating layer (C). Since the coating layer (C) is used to form the grooves (22b, 22c), the grooves (22b, 22c) can be formed by a printing process with a printing apparatus. <IMAGE></p> |
